Relatively little research has been undertaken to determine what insomnia is and how insomnia may confer risk for other disease states. The lack of research may be due, in part, to the fact that the insomnia phenotype lacks objective markers, and that this is especially true for the phenomenon of cognitive arousal. This concept, while critical 1) to the patient's experience of insomnia and 2) for many etiologic theories about insomnia, is traditionally measured only by self-report. An alternative may be to use performance based measures of attentional processing. Experimental 'probe'tasks, indexing processing speed, have been used productively to explore the role of cognition in relation to wide range of psychological and habit disorders. To date, three types of task have been evaluated in patients with insomnia. These studies have successfully demonstrated the phenomenon of sleep-related attention bias, in patients with Psychophysiologic Insomnia, to semantic and pictorial stimuli. Proposed Study: The aim of the present study is to further explore the critical components of attentional processing with a view to identifying a candidate 'marker'for insomnia. In order to accomplish this, three domains of cognitive arousal will be evaluated in 4 groups. These domains are subjective mental experience (self report), performance (attentional processing) and cortical activity (qEEG). Self-report data and facial EMG will also be used to index other dimensions of arousal. The four subject groups will be Healthy Good Sleepers, patients with Psychophysiologic Insomnia and patients with Insomnia associated with Depression (acute and remitted). The primary goals will be to determine ) the extent to which the groups differ across these three cognitive domains, 2) the component processes of attention most critical to this differentiation and 3) the relative predictive utility of each of the attentional measures (viz. diagnosis).